The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The hidden lair of an alchemist rediscovered in a 2002 flood.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

A two-inch thick solid brass rod that extends an astounding one kilometer straight into the earth.

This unique Renaissance castle was turned into a home for Nazi occultism.

One of the largest remaining ancient burial mounds of the 10th century.

The 14th-century ruins are said to contain healing powers.

Repurposed space and ultra-modern construction collide to create this geometric wooden spectacle.

This historic stone bridge has an entire neighborhood clinging to its sides.

This renaissance château was home to an infamous witch hunter who sent a hundred suspected witches to their deaths.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

This attraction was abandoned after the Chernobyl disaster.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

Every part of this unusual home is built into the sandstone rock.

This Gothic church was wheeled in its entirety to a new location a half a mile away.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

This man-made mound monument was built out of soil from all across the Polish empire.

Real bones which are said to have belonged to a Polish dragon.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

In the midst of a living monument to Soviet social engineering, Polish Catholics built this church by hand.